1. Field of the Invention
This invention relates to improvements in an internal combustion engine of the split type which will operate on less than all of its cylinders with the remaining cylinders being supplied with exhaust gases reintroduced thereinto under normal or light load conditions.
2. Description of the Prior Art
It is generally known that engine operation is more economical if each cylinder of the engine is run under relatively high loads. However, under most vehicle operating conditions the engine is operating under relatively light loads resulting in uneconomical fuel consumption. Accordingly, it is desired to shift engine operation into a split or part cylinder engine mode wherein the engine operates on less than all of its cylinders such as by cutting off air and fuel flow to the remaining cylinders during normal or light load operation with the remaining cylinders being brought into operation only after the load on the engine exceeds a given value. In this way it is possible to increase the load on each of the active cylinders, which results in greater overall operating economies for the engine.
For the purpose of reducing pumping losses in the inactive cylinders thereby making engine operation more economical, it is common practice to re-introduce exhaust gases into the inactive cylinders so as to maintain them at substantially atmospheric pressure.
In introducing blow-by gases into the intake passage of the split engine in such a manner as is done in normal internal combustion engines, a particularly difficult problem occurs in that the intake system associated with the inactive cylinders is soiled greatly with solid carbon. Blow-by gases, unburned air-fuel mixture leaking from the combustion chamber to the crankcase past the piston rings fitted between the piston and the cylinder wall, include a great amount of oil. The oil sticks to the wall of the intake system associated with the inactive cylinders and combines with soot included in re-introduced exhaust gases to form a pile of solid carbon thereon.